Pedestrian trucks are well known in the art and the most common type is a pedestrian pallet truck. Such trucks have a pair of front forks for engaging with and lifting a pallet clear of the ground. The operator steers the truck using a rear tiller to control one or more rear steered wheels. The tiller handle will optionally have operator controls for engaging and controlling a drive motor (if the truck is a powered, driven truck), the operation of the forks, and so on.
FIG. 1 shows a conventional pedestrian controlled powered truck 10 for handling palletised and compact loads. The truck is fitted with a steered driven wheel 12 at the rear end 14. The steering is controlled via a tiller arm 16. The truck is fitted with a non-driven castor wheel 18 at the front end 20 on the right-hand side 22. The truck is also fitted with a non-driven wheel 24 on the front left-hand side 26. This non-driven front wheel 24 is coupled to a hydraulic cylinder 28 which keeps the wheel 24 parallel to the forks 30 (i.e. at an angle which will be referred to herein as zero degrees).
The truck 10 is fitted with electric power steering (not shown). The tiller's rotation, clockwise or anti-clockwise about the tiller's vertical pivot axis, which is approximately vertically above the rear steered driven wheel 12, is translated directly to the steering angle of that rear wheel 12. (The tiller may also pivot about a horizontal axis, allowing it to tilt between a near-vertical and a horizontal position, but such movements do not affect steering except insofar as the tiller also pivots around its vertical steering axis.) The truck of FIG. 1 is configured to operate in a first mode of operation, i.e. the forward and reverse drive directions are aligned toward the front 20 and rear 14 ends, as indicated by the arrows 32. (As used herein, forward means towards the ends of the forks, when the truck is in the first mode of operation; when in the second, sidewards mode described below, forward is in the direction away from the operator's end of the tiller with the tiller trailing the truck).
FIG. 2 shows same truck when operating in a second mode of operation. The hydraulic cylinder 28 has now rotated the front left-hand wheel 24 perpendicular to the forks (i.e. 90 degrees). The front left-hand wheel 24 has only 2 positions, 0 degrees and 90 degrees. The operator can select either of these 2 positions with a switch on the tiller handle 34. The operator has also turned the rear wheel 12 by 90 degrees via the tiller 16 which is now disposed generally perpendicular to the forks 30. The right-hand castor wheel will freely follow the direction of travel.
When in this mode of operation the truck can be used to handle long loads more easily. The “forward” and “reverse” directions of travel are now perpendicular to the forks also as indicated by the arrows 32.
Tiller steering can be somewhat unintuitive, and is particularly so when the tiller is being used to steer a wheel which (as in the configuration of FIG. 2) is mounted on one side of the truck, rather than being a central rear steered wheel as in the FIG. 1 configuration. While an operator may learn by trial and error how to manoeuvre the truck of FIG. 2, such on-the-job learning is potentially dangerous when handling a long load which projects out from the forks on either side by perhaps a few meters, in what will typically be an industrial or workplace environment with other workers and other machinery in operation.
Steering arrangements from vehicles where the operator is seated in a fixed position tend not to be of assistance due to the very different outlook of a pedestrian operator who is walking behind a truck and is in the mindset of “pushing” the truck and steering with large physical tiller movements when driving the truck forwards ahead of himself or herself.